Paper-sizing composition



Patented Apr. 29, 1941 PAPER-SIZIN G COMPOSITION Earle It. Edson,Gloucester, and Charles Quincy Ives, Reading, Mass, assignors to LePages Inc., Gloucester, Mass, a corporation of Massachusetts No Drawing.

12 Claims.

This invention relates to a paper-sizing composition and more especiallyto a rosin-starch composition whose starch component is possessed ofsuch chemical and physical properties as to enable the realization ofsized paper products of improved character, for instance, markedlyimproved water-repellence, improved bursting-strength, tear-resistance,fold-endurance, and other physical characteristics.

In producing rosin-sized papers, it is well known that thewater-repelling or sizing effeeton the paper sheet is influenced by thecomposition of the rosin size added to the papermaking stock.

, Thus, under given conditions, the greater the free rosin content ofthe rosin size, the greater is the water-repelling or sizing effectattainable in the finished paper product. It is hence understandable Whymany paper manufacturers have within recent years adopted the practiceof using rosin sizes of high free rosin content. Indeed, some rosinsizes being used currently on a commercial scale consist essentially ofan aqueous dispersion of substantially only free or unsaponified rosin,the dispersion being stabilized by a relatively very small amount ofprotective colloid, such as rosin soap and/or alkali-caseinate.

An important aspect of the present invention is the provision of asizing composition containing besides rosin size .a particular kind orform of starch that evidently serves the function of maintaining thefree rosin content of the rosin size, whatever such free rosin contentmay be, at a maximum, and that hence enables the realization of paperproducts of maximum waterrepellence for a particular rosin size usage.More specifically, the sizing composition hereof contains as its starchcomponent a so-called starchconversion product in acidic condition andexhibiting, among other characteristics, substantial solubility in waterand relatively low dextrin content, as determined by a method presentlyto be indicated. The sizing composition hereof is prepared in anexceedingly simple way, namely, by mere substantially homogeneousadmixture of substantially dry, pulverulent, rosin size andsubstantially dry, pulverulent, starch-conversion product of theparticular character already described. The resulting substantiallyphysically homogeneous rosin-starch composition presents the advantagesthat it can be stored and shipped economically with no significantdeterioration, even when exposed to widely varying temperature,humidity, and other atmospheric conditions, and that it can be addeddirectly to papermaking stock, as in a beater engine, and otherwise han-Application March 13, 1939, Serial No. 261,666

dled much in the same way as when using rosin size, as ordinarily, indry or wet forms for sizing papermaking stock.

While we cannot explain with precision the mechanism underlying theimproved results attain-able through the use of the rosin-starchcompositions hereof, yet some factors known to us contribute importantlyto these results. To begin with, the admixture of substantially dryrosin size having some rosin soap content with the substantially drystarch-conversion product is attended by an envelopement or coating ofthe rosin size particles with such product. Upon addition of thecomposition consisting essentially of starch-coated rosin size particlesto an aqueous suspension of paper-making stock, as in the beater engine,the aqueous medium tends to dissolve the soluble content of theconverted starch coatings or envelopes before the rosin size particlesthemselves are acted upon by the aqueous medium and put into solution ordispersion in the aqueous medium.- It is accordingly seen that theaqueous medium is, immediately prior to or concurrently with thesolution or dispersion of the rosin size particles, put in acidcondition by the acidic, converted starch for the solubilizing ordispersing action on the rosin size particles. Our hypothesis is thatthe converted starch, by reason of its acidic condition, not onlycontrols or influences the kind of solution or dispersion ef fected uponthe rosin size particles in the direction of yielding a solution ordispersion of microscopically fine or colloidal particle size but alsopreserves or increases the free rosin content of the rosin size. In thislatter connection, it must be borne in mind that the acidic, convertedstarch, as it contacts with and is dissolved at least partially in theaqueous medium alongwith the rosin soap content of the rosin size, isconducive, if anything, to reaction between the rosin soap and theacidicaqueous medium to form free rosin or abietic acid. It is ourfurther theory that, in the course of adding the rosin-starchcomposition hereof to papermaking stock, the free rosin content of suchcomposition is preserved, if not increased. Moreover, We have observedthat in appying our sizing composition to papermaking stock there is noobservable generation in the papermaking stock of agglomerates of rosinsize. In other words, the rosin size particles are dissolved ordispersed with no observable formation of palpable rosin particles; andsuch increase in free rosin as may occur during admixture of the sizingcomposition hereof with the papermaking stock is evidently in the formof microscopically or colloidally fine free rosin particles. Whether ornot our hypotheses are correct, the fact is that papermaking stockssized with the composition hereof lead to paper products of higherwater-repellence than when sizing is accomplished under similarconditions with similar amounts of the rosin size and converted starchadded separately to the papermaking stock and phenomenally higher thanwhen sizing is accomplished under similar conditions with similaramounts of the rosin size and a1- kali-converted starch addedconcurrently or separately to the papermaking stock. 7

Another important advantage inhering in the sizing composition hereof isits low foaming prop erty even when its rosin size component is of veryhigh rosin soap content. When such rosin size is applied to papermakingstock concurrently with an alkali-converted starch, as in the beaterengine, foaming tendency is so pronounced that it becomes necessary touse so much anti-foaming agent, such as kerosene, to avoid pin holes andother physical defects in the paper product as to detract seriously fromthose qualities supposed to be imparted thereto by the rosin size andstarch, including water-repellence, burstingstrength, tear-resistance,and fold-endurance. On the other hand, such foaming as may be occasionedby the application of the rosin-starch sizing composition hereof topapermaking stock in the beater engine is so small or inconsequentialthat no anti-foaming agent whatever need be added to the sized stock inarriving at a paper product of the desired substantial freedom from pinholes or other physical defects. The very low or negligible foamingproperty in the rosinstarch sizing composition hereof is attributable tothe fact that, although the rosin-size component may originally be indistinctly alkaline condition, its alkalinity is largely orsubstantially completely offset or neutralized by the acidic, convertedstarched component, wherefore, although the rosin-size component byitself induces marked foaming under agitation in Water, the compoundingtherewith of acidic, converted starch largely or substantiallycompletely eliminates such foaming tendency; It might be remarked thatit is well known in the papermaking industry that foam formation in anaqueous suspension of papermaking stock is fostered by distinctlyalkaline rosin size and that the extent of foaming is related to thedegree of alkalinity in the stock or the rosin size added thereto. It isfor this reason that the preferred rosin-size composition hereof isprepared With rosin-size and acidic, converted starches in such relativeproportions and/or in such conditions of alkalinity and acidity,respectively, as to yield in the papermaking stock prior to the additionof alum or other precipitant for the composition a substantially neutralcondition, that is, pH value of substantially 7.

While not limited thereto, the present invention will now be describedin terms of exemplary procedure that has been established as yielding arosin-starch composition satisfactory for the purposes hereof and alsoin terms of exemplary papermaking procedure involving the use of suchrosin-starch composition in the production of a sized paper product ofthe desired and improved character. In preparing a rosin-starchcomposition answering the purposes hereof, one may start with any of theknown dry rosin sizes of commerce. For instance, the dry rosin sizeadopted may consist essentially entirely of pulcontent desired.

verulent rosin soap; and it may contain only a slight amount ofadventitious moisture, say, about 1%. The acidic, converted starchadopted may be a pulverulent material prepared by the heat-treatment orcalcination of any suitable form of raw starch, say, tapioca flour; andthe heat-treatment or calcinaticn of the raw starch is preferablyconducted under combined conditions controlled to yield an acidic,converted starch of the particular solubility and dextrin The combinedconditions of heat-treatment of the raw starch may include not onlyproperly correlated elevated temperature and time factors but also, ifdesired, the correlation of the elevated temperature and time factorswith a catalyzing factor provided in the sphere of the starch-convertingreaction by preliminarily moistening or spraying the raw starch granuleswith an amount of water or acidic, aqueous medium so limited (e. g, inamount less than about 25%, based on the dry Weight of the raw starch)as to avoid substantial gelatinization of the starch granules. Forpreparing the rosin-starch composition hereof, we have found that anacidic, converted starch having substantial solubility, for instance,upwards of about 20%, is desirable; and we have further found that suchstarch functions conjunctively with the rosin size to best advantage, asregards increasing the water-repellence and improving thebursting-strength, tear-resistance, fiex-endurance, and other qualitiesof the finished paper products, when its dextrin content is downwards ofabout 60% and is preferably as close to a substantially zero percentageas is possible to achieve by such heat-treatment or calcination as hasbeen described and as will further be described hereinafter. Thestarch-solubility value given herein for the acidic, converted starch isdetermined by adding 5 parts of the starch to 100 parts of Water at F.and mixing the starch in the water for not less than about 3 hours, atthe end of which time the dissolution of the soluble solids is ensured.The waterstarch mixture is then filtered through a suitable filtermedium, such as filter paper, and the filter medium carrying theundissolved starch-residue accumulation is dried at, say, 230 F., tobonedryness and Weighed. The undissolved starch residue may then becalculated from the original or bone-dry weight of the filter medium andthe percentage of the soluble and insoluble solids in the convertedstarch readily evaluated. It is usually desirable to add to thewater-starch mixture a predetermined or weighed amount of suitableadsorbent or so-called filter aid, such as freshly precipitated aluminumhydroxide or Filtercel, which adsorbs the undissolved but fine solidsresidue and hence does away with such error as might result from theescape of fine undissolved particles through the filter medium. Whereasescape of undissolved fine particles is evidenced by a cloudy ormilkyappearance in the filtrate, the addition to the water-starch mixturebeing filtered of a suitable amount of adsorbent makes for a. clearfiltrate. The dextrin content given herein for the acidic, convertedstarch is determined by the method of Babington, Tingle and Watson, asdescribed under the caption The Examination of Commercial Dextrin andRelated starches in the Journal of the Societyof Chemical Industry, vol.37 (1918), p. 257. Such solubility and dextrin values as appear in theappended claims should hence be understood as having been determined bythe particular methods herein prescribed.

The substantially dry rosin-starch composition hereof may be produced inan ordinary dry mixer or churn by adding the substantially dry rosinsize and the substantially dry acidic, converted starch to the mixer andoperating the mixer until substantial physical homogeneity in theresulting composition is ensured. While the composition hereof may havea dry rosin size content ranging from about 10% to 90%, based on the dryweight of the composition, and. a dry starch content ranging from about10% to 90%, based on the dry weight of the composition, the compositionis especially advantageous when it has a rosin size content and a starchcontent each ranging from about 40% to 60%. The ease and simplicity ofpreparing the composition hereof will be appreciated from the fact thatin a suitable dry mixer, for instance, a Day mixer, the substantialphysical homogeneity desired in the composition is reached in a mixingperiod of only about one-half hour. The resulting composition may beshipped in bulk, as in barrels; or it may be put up into package form,for instance, in sealed paper bags each holding. say, five pounds andhence useful for sizing a particular portion or weight of papeimakingstock in the beater engine. Assuming, for example, that a beater engineis to be charged or furnished with a thousand pounds of papermakingstock on a dry basis and that it is desired to produce from such stock afinished paper product of a sizing solids content of substantially 3%,the beater operator can proceed to add to the engine, along with thepapermaking stock, six sealed bags or units of the sizing compositionhereof, whereupon he can start the engine along with the necessaryamount of circulating water and continue beating the stock until it hasacquired the hydration or consistency desired for papermaking. Duringthe beating operation, the paper bags are disintegrated or pulped alongwith the papermaking stock so that the resulting stock has thesubstantial homogeneity or consistency necessary for papermaking. Itmight be noted that the retention of the sizing solids of thecomposition hereof by the papermaking stock and their sizing o-rwater-repellent value in the finished paper product are notsignificantly impaired as a result of their having been beaten ormanipulated along with the papermaking stock. It is probably by virtueof the microscopically fine or colloidal condition of the sizing solidsand their non-coalescing character that the functions desired thereofremain substantially unimpaired during the beating operation, for, inordinary papermaking practice, it is customary to add rosin or othersize when the beating operation is nearing completion or has beencompleted so as to realize the desired maxi mum from the size. It isplain, therefore, that one aspect of the present invention is that itmakes possible the minimization of costs in the papermaking mill, sinceit becomes unnecessary to weigh out the sizing composition or handle itin loose, dusty condition as heretofore. On the contrary, the sealedbags or units of the composition hereof may be dumped as such into thebeater engine and, being units of sufficiently small size to bedisintegrated or reduced as they enter into the ingress afforded by thebed plate and the beater roll of the engine along with the papermakingstock, the distribution or dispersion of the sizing solids occurs at thesame time as the papermaking stock is being hydrated and otherwiseconditioned for papermaking. In other words, the present invention doesaway with a size-mixing period subsequent to the beating operation suchas has been usual in the practice of sizing papermaking stock in thebeater engine. Again, the sealed bags or units of the sizing compositionhereof are drawn into the zone of the beater-roll action and under theaqueous medium associated with the papermaking stock, wherefore,dissolution and dispersion of the sizing solids take place rapidly underwater throughout the papermaking stock and there is hence no tendency,as in ordinary papermaking practice, for the sizing solids to stick tothe walls or other parts of the beater engine, or to fly away as drydust into the atmosphere of the beater room and thus cause nuisance aswell as constitute a loss.

Using specifically the rosin-starch composition hereof at a rosin sizeand starch solids content of 50% each in producing a sized paper productof a sizing solids content of substantially 3%, the procedure may bealong the lines hereinbefore indicated. That is to say, sealed bags orunits of the substantially dry sizing composition hereof may be addedalong with the starting papermaking stock to the beater engine, 30 partsby weight of such composition and 1000 pounds of papermaking stock on adry basis constituting the beater furnish. On the other hand, it is, ofcourse, possible to add the sizing composition hereof after thepapermaking stock has been beaten or hydrated to the desiredconsistency. Irrespective of the particular stage of the beatingoperation at which the sizing composition is added, one arrives at asubstantially physically homogeneous, sized papermaking stockconditioned for the addition of alum or equivalent precipitant capableof throwing down and fixing the sizing solids on the fibers. The alum isadded in amount to precipitate and fix substantially all the fixable,dispersed sizing solids associated with the papermaking stock, forinstance, in amount predetermined to impart a distinctly acid conditionto the beater water, say, a pH value of about 5. We have observed thatthe ultra-finely or colloidally dispersed phase of sizing solids hereofis precipitated and fixed substantially entirely in the desired veryfine particle size upon the fibers of the papermaking stock when theappropriate amount of alum is admixed with the stock, insomuch that thebeater water is practically water-white or clear. That the sizing solidsof the composition hereof are retained substantially in their entiretyby the papermaking stock is also evidenced by the substantial clarity ofthe white water drained from the papermaking machine. Of course, thesized papermaking stock is, after dilution to the desired fiber contentas ordinarily, delivered to the papermaking machine; and, with the stockat diluted or papermaking consistency, fine sizing solids would, unlessproperly fixedto or retained by the stock, be carried away with theexcess water drained from the papermaking machine, as is the case when,for example, raw starch is added to papermaking stock in accordance withprior art practice.

When a papermaking stock, such as kraft pulp, is sized in the mannerjust described and is converted into a paper of a thickness and basisweight comparable to ordinary kraft wrapping paper, for instance, athickness of substantially .007" and a basis weight of substantially 70pounds (i. e., the weight of 480 sheets whose dimensions are 24" x 36"),it is found that the resulting dried paper sheet has phenomenally highwater-repellence, as tested by the usual water-ink floatation method.Thus, the finished paper sheet hereof, when floated on a bath ofwater-soluble ink or dye, displayed no sign of stain-through of the inkfrom the under face of the sheet to the upper face for a period longerthan two hours. On the other hand, when a dried starch previouslyalkalinized or gelatinized in alkali solution is compounded withsubstantially dry rosin size under the same conditions as those used inthe preparation of the rosinstarch composition hereof and then put touse for sizing papermaking stock under the same conditions, includingproportionality of both rosin and starch to the papermaking stock, asthose prevailing in the foregoing example of procedure hereof, it isfound that a finished paper product having a thickness of substantially.007" and a basis weight of substantially '70 pounds is of comparativelyvery low water-repellence, since it exhibits a stain-through period notexceeding about 30 minutes by the usual water-ink floatation method.Comparable marked improvement in the water-repellence of paper productsis attainable pursuant to the present invention in the production ofpapers of various thicknesses and/or basis weights and/or rosin-starchsizing solids contents. It might be further observed that paper productsprepared accordant with the present invention are also of superior bursting-strength, tear-resistance, and fold-endurance. Such latter improvedphysical properties are probably traceable to the high bondingeffectiveness of the acidic, converted starch entering into therosin-starch composition hereof. So far as concerns uniformity ofdistribution of the rosin and starch sizing solids in the paper productshereof, it is noteworthy that such products are practically free fromsuch defects as resin specks or starch shiners observable with the nakedeye, which specks or shiners bespeak the presence of agglomerates orunduly coarse particles of rosin size or starch in the papermakingstock. It is evidently the case that not only is the acidic, convertedstarch of the rosin-starch composition hereof substantially uniformlydispersed as ultra-fine or colloidal particles throughout thepapermaking stock but further that the dissolved or colloidallysuspended starch particles influence through their protective colloidaleffect the precipitation of the rosin in the sense that the precipitatedrosin particles are substantially uniformly thrown down on thepapermaking fibers in very fine or colloidal particle form.

From the standpoint of developing the very best physical qualities inthe paper products hereof, it is highly desirable to use an acidic,starch conversion product whose acidity is developed during aheat-treatment or calcination of raw starch under conditions controlledto yield an acidic, starch-conversion product possessed of theproperties of solubility and dextrin content already indicated. However,it is also possible to use for the purposes hereof an acidicstarch-conversion product whose acidity is generated during thehydrolysis of raw starch in suspension in an acidified aqueous medium,as is known to those skilled in the art. When such latter acidic,hydrolyzed, starch-conversion product is used in preparing therosin-starch composition hereof, it should be understood that theacid-hydrolyzed, aqueous starch solution is, as by spray-drying ordrum-drying treatment, brought to the substantially dry, pulverulentform required for compounding with the rosin size. The acid-hydrolyzingtreatment of the raw starch in aqueous suspension may be performed withone or more suitable acidic reagents, such as hydrochloric acid, aceticacid, etc., at the desired temperature, preferably at an elevatedtemperature up to the boiling point of water. The acidic, hydrolyzed,starch-conversion product thus produced by treating the raw starch insuspension in an acidified aqueous medium will be termed hereinafter ahydrolyzed, acidic, starch-conversion product, as distinguished from theexpressions acidic, converted starch or acidic, starch-conversionproduct, which are used herein to denote both an acidic, hydrolyzed,starch-conversion product and astarchconversion product prepared byheat-treating or calcining essentially dry or solid raw starch undercontrolled conditions either in the absence or presence of a limitedv.amount of wateror acidic catalyzing agent, which agent in the form ofan aqueous or liquid solution of appropriate strength may be applied, asby spraying, substantially uniformly to the raw starch for the purposeof moistening the latter for the heattreatment. A distinctly preferredacidic catalyzing agent for preparing acidic, heat-treated or calcinedstarch-conversion products useful for the purposes hereof consistsessentially of an aqueous solution of hydrochloric acid, acetic acid,and formaldehyde. Such solution may be advantageously applied to the rawstarch in amount to associate substantially uniformly with the starchgranules about 0.03% to 0.5% hydrochloric acid, about 0.01% to 0.5%acetic acid, and about 0.03% to 2.0% formaldehyde, based on the dryweight of the starch. However, as above stated, any suitable acidiccatalyzing agent may be used in the calcining treatment of the rawstarch, according to the particular results desired; and. the resultingacidic, calcined, starch-conversion product may be used in thepreparation of the sizing compositions hereof. The acidic, heat-treatedor calcined starchconversion product used for the purposes hereof, whichhas been prepared in the absence of hydrolyzing treatment of the rawstarch in suspension in aqueous acidic medium, will be termedhereinafter acidic, calcined, starch-conversion product so as todistinguish from the expressions acidic, hydrolyzed, starch-conversionproduct and acidic, starch-conversion product or acidic, convertedstarch. The acidic, calcined, starch-conversion product used for thepurposes hereof is characterized by its swellability or gelatinizingproperty in water to yield highly viscous or gel-like aqueous solutionswhen mixed with about 1 to 4 times its Weight of water at 70 F.; andsuch property of swellability has been found to go hand in hand with thedevelopment of the best physical properties in paper products sized withthe rosin-starch sizing composition hereof. On the other hand, theacidic, hydrolyzed, starch-conversion product yields relatively verythin or highly fluent aqueous solutions when admixed with about 1 to 4parts of its own weight of water at 70 F.; and, When it constitutes thestarch component of the rosinstaroh composition hereof, the paperproducts sized with such composition are of definitely lower physicalproperties than the sized paper products whose starch-sizing solids arederived from a rosin-starch composition. hereof containing as its starchcomponent an acidic, calcined, starch-conversion product. It is likelythe case that acid-hydrolyzingtreatment of raw starch in suspension inacidic aqueous mediumso degenerates or degrades the starch molecule thatits bonding tenacity or power in cementing together the paper fibers isdefinitely impaired. The measure of impairment can usually be forecastin terms of the relatively low viscosity, or vice versa, the relativelyhigh fluidity of such hydrolyzed or degenerated starch-conversionproduct. While it may be possible to control or repress the hydrolyzingreaction on raw starch in suspension in acidic aqueous medium so as toarrive at an acidic, hydrolyzed starch-conversion product possessed of acomposition and physical characteristics approximating that of anacidic, calcined, starch-conversion product, nevertheless such controlpresents difficulties and, in any event, an acidic, calcined,starch-conversion product is far more economical of production, since nosuch after-treatments as dewatering, drying, and pulverization or theexpensive apparatus, labor, and other costs incident to theseafter-treatments figure in the preparation of such latterstarch-conversion product.

So efitlcacious is an acidic, calcined starch-conversion product alongwith rosin size in enhancing the physical properties of rosin-sizedpaper products, including the water-repellenoe of such products, that itneed not necessarily be applied to or incorporated into the papermakingstock concurrently with or as protective coatings about thesubstantially dry rosin size. The fact is that another important phaseof the present invention involves the admixture with papermaking stockat a suitable stage of its heating or after its beating has beencompleted of the rosin size and the water swellable orwater-gelatinizable, acidic, calcined starch-conversion product as anentity separate or distinct from the rosin size, which latter size mayeven be used in wet or water-dispersed form. It may be preferable toadmix with the papermaking stock the acidic, calcined, starohsence ofrosin specks or starch shiners in such products. The point is that solong as the waterswellable, acidic, calcined, starch-conversion producthas been dissolved or dispersed substantially uniformly throughout thepapermaking stock along with the rosin size prior to the addi-.

tion to the stock of the alum or equivalent precipitant, both the starchand rosin are substantially completely precipitated or fixed in thedesired ultra-fine or colloidal condition substantially uniformlythroughout the stock, the swollen or gelatinized starch particlesevidently exerting the desired influence in the precipitating orreacting sphere to maintain the precipitated rosin particles in thedesired uniformly ultra-fine or colloidal condition. When the rosin sizeis ap plied independently of the water-swellable, acidic, calcined,starch-conversion product to the papermaking stock in the form of anaqueous or waterdispersed composition, it may be advantageous to userosin size of especially high free rosin content, for instance, a freerosin content so high as to constitute the major portion, if notsubstantially the entire, sizing solids content of the rosinsizingcomposition, in which case such composition may contain an extraneousstabilizer or protective colloid, such as casein. In other words, whenthe principles of the present invention are utilized in such manner asnot to increase the free rosin content of the rosin-sizing compositionused for the purposes hereof, it may be preferable, as when usingaqueous rosin-sizing composition, to provide sufficient free rosin inthe original rosin-sizing composition to develop the desired very highwater-repellence in the paper products hereof while maintaining therosin-sizing solids substantially completely at such ultra-fineness orcolloidality as is consonant with the substantial absence of rosinspecks or agglomerates observable to the naked eye in the paperproducts. Apropos of the matter of using rosin size of high free rosincontent, papermaking mills sometimes experience trouble with such sizebecause hardness in the water or extraneous contaminations in thepapermaking stock tend to induce premature precipitation andagglomeration of the free rosin particles into unduly coarse particles.Such trouble is avoided when such rosin size is added pursuant to thepresent invention more particularly after thestock has been infusedsubstantially uniformly with an acidic, calcined, starchconversionproduct.

The term "starch is used in the foregoing description and in theappended claims in its comprehensive sense to include starches ofvarious derivations, for instance, such amylaceous substancesas tapiocaor sago fiour, the starches of maize, wheat, potato, etc., and starchescontaining more or less protein or other matter. Again, the expressionrosin size is used herein and in the appended claims in itscomprehensive sense to include not only straight rosin sizes or soapsand rosin sizes containing more or less free rosin but also compoundedrosin sizes, for instance, rosin wax sizes. It should be understood thatvarious kinds of cellulosic fibers may constitute the papermaking stockhereof, including wood pulps, such as Kraft, sulphite, soda, andmechanical wood pulp; also cotton fiber or rag halfstufi. So; too,various non-cellulosic fibers, such as the various animal and mineralfibers, may form part of the papermaking stock together with suchcustomary papermaking ingredients as fillers, colors, dyestuffs, etc.

The present invention may be applied in ways other than those alreadydescribed. For instance, the rosin-starch sizing composition hereof maybe admixed with the papermaking stock and precipitated or fixed thereonat any suitable stage of papermaking beyond the beater engine,'say,whileit is on its way to the papermaking machine; It is also possiblefor the papermaker to dissolve or disperse in an appropriate amount ofwater thesubstantially dry rosin-starch composition hereof before suchcomposition is admixed with and precipitated or fixed on the papermak"ing stock. In otherwords,when added to the stock, such composition maybe in wet-compounded condition (i. e., in already-dissolved orwaterdispersed condition) rather than being added in preferablydry-compounded condition to the water associated with the papermakingstock or being preferably wet-compounded in situ in the aqueouscomponent of the papermaking stock. In some instances, as when thepapermaker has equipment for preparing aqueous size compositions,dry-compounding of the rosin-starch composition hereof may be dispensedwith in favor of admixing the rosin size in the presence of water (e.g., an aqueous rosin-size composition containing a substantial amount offree rosin) with an acidic, starch-conversion product of the kindhereinbefore described, incorporating the resulting wet-compounded,rosin-starch composition into the papermaking stock, and precipitatingor fixing the composition on the stock. In such instances, the use of anacidic, calcined, starch-conversion product is also preferred for thereasons already stated. It is possible to utilize the'principles of thepresent invention in other ways without departing from the spirit orscope of the invention as defined in the appended claims.

We claim:

1. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct having a dextrin content downwards of about 60% and substantialsolubility in water at 70 F.

2. A substantially dry composition particularly adapted for sizingpapermaking stock and. comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct having a solubility in f water at 70 F. upwards of about 20%.

3. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct having a dextrin content downwards of about 60% and a solubilityin water at 70 F. upwards of about 20%.

4. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct capable of yielding when admixed with about 1 to 4 times its ownweight of water at 70 F. a highly viscous solution.

5. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined, starch-conversionproduct having at least about 20% solubility in water at 70 F. andcapable of yielding when admixed with about 1 to 4 times its own weightof water at 70 F. a highly viscous solution.

6. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined, starch-conversionproduct having a dextrin content downwards of about 60%, a solubility inwater at 70 F. upwards of about 20%, and capable of yielding whenadmixed with about 1 to 4 times its own weight of water at F. a highlyviscous solution.

7. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct, said rosin size and said starch-conversion product each beingpresent in said composition in amount ranging from about 40% to 60%,based on the dry weight of said composition.

8. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined starch-conversionproduct having a dextrin content downwards of about 60% and a solubilityin water at 70 F. upwards of about 20%, said rosin size and saidstarch-conversion product each being present in said composition inamount ranging from about 40% to 60%, based on the dry weight of saidcomposition.

9. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined,

starch-conversion product having a solubility in water at 70 F. upwardsof about 20% and capable of yielding when admixed with about 1 to 4times its own weight of water at 70 F. a highly viscous solution, saidrosin size and said starchconversion product each being present in saidcomposition in amount ranging from about 40% to 60%, based on the dryweight of said composition.

10. A substantially dry composition particularly adapted for sizingpapermaking stock and comprising substantially dry rosin size particlesenveloped by substantially dry, acidic, calcined, starch-conversionproduct having a dextrin content downwards of about 60 a solubility inwater at 70 F. upwards of about 20%, and capable of yielding Whenadmixed with about 1 to 4 times its own weight of water at 70 F. ahighly viscous solution, said rosin size and said starchconversionproduct each being present in said composition in amount ranging fromabout 40% to 60%, based on the dry weight of said composition, and saidcomposition affording when admixed with water a substantially neutralaqueous medium.

11. A composition especially adapted for sizing papermaking stock andcomprising rosin size particles enveloped by an acidic, calcinedstarchconversion product having a dextrin content downwards of about 60%and a solubility in water at 70 F. upwards of about 20%.

12. A composition especially adapted for sizing papermaking stock andcomprising rosin size particles enveloped by an acidic, calcinedstarchconversion product having a dextrin content downwards of about60%, a solubility in water at 70 F. upwards of about 20 and a capabilityof yielding when admixed with about 1 to 4 times its own Weight of waterat 70 F. a highly viscous solution.

EARLE R. EDSON. CHARLES QUINCY IVES.

